The present invention relates to a method and apparatus for the manufacture of a roll of coiled barbed strap, and more particularly to such a coiled barbed strap the loops of which, in pairs, are provided with an odd number of clamps of at least three per loop and are axially separable from each other within each roll, such that each strap loop passes around one screw line.
A prior art method of producing coiled barbed strap is illustrated in FIGS. 1 through 4 of German Patent 23 48 714. According to the thus known method, the barbed strap is coiled, the clamps corresponding to the number of clamps per coil are placed on two adjacent loops and the barbed strap is cut after the last clamp is placed. To this end the barbed strap loops are produced with the aid of a cylindrical winder in the core through continuous coiling of the barbed strap, which is under tension, whereby the winder is continuously displaced in the direction of its longitudinal and rotational axis in accordance with the inclination of the strap loops, so that the winder performs a screw-type movement. Prior to the beginning of this screw-type movement, the beginning end of the tangentially supplied barbed strap is detachably connected to one end of the winder. A rotary table is arranged coaxially to the winder, which table revolves synchronously with the winder but remains still axially. This rotary table supports a plurality of clamping devices, namely five, for example, which corresponds with the number (five) of clamps for every two loops of the barbed strap, so that during the uninterrupted rotation of the winder, each clamping device is activated one for every two rotations, thereby connecting two adjacent loops of the barbed strap by a clamp.
It is disadvantageous in the known method that the lengths of the strap loops produced by winding the barbed strap onto radial ribs of the winder can vary as a result of failures during production (stamping and edging process) of the barbed strap and/or as a result of nonuniform welding of the cross bars of the winder and that, in some cases, the strap sections, which are crimped to assist in the crease closure of the crimped barbed strap around a support wire, do not rest with sufficient phase-equal precision beneath the clamping devices to allow the clamping to be performed without difficulty.